Portable belt sanding machine



Dec. 18, 1956 A. N. EMMONS 2,774,198

PORTABLE BELT SANDING MACHINE Filed April 5, 1955 3 Sheets-Sheet l v V m INVENTOR.

RTHUR N. EMMQNS"; BY 9m 11 Dec. 18, 1956 A. N. EMMONS 2,774,198

PORTABLE BELT SANDING MACHINE Filed April 5, 1955 3 Sheets-Sheet 2 INVENTOR.

ARTHU N. EMMONS BY 9M fifi'ornC'j Dec. 18, 1956 A. N. EMMONS 2,774,198

PORTABLE BELT SANDING MACHINE Filed April 5, 1955 3 Sheets-Sheet 5 INVENTOR.

ARTHUR N. EMMONS BY a p: Afiomu United States Patent PORTABLE BELT SANDING MACHINE Arthur N. Emmons, Nedrow, N. Y., assignor to The Porter-Cable Machine Company, Syracuse, N. Y., a corporation of New York Application April 5, 1955, Serial No. 499,381

3 Claims. (Cl. 51-170) This invention relates to portable self-contained, power-operated, belt sanding machines.

These machines consist generally of a frame in which the driving and idler rolls are journalled, and in, or on which, an electric motor is mounted and which is operatively connected to the driving roll to effect rotation thereof for movement of the endless abrasive belt trained over the driving and idler rolls. This type of sanding machine is used very extensively and functions to efliciently and rapidly remove large amounts of material, preparatory to rendering the surface of the work ready for the application of a finish.

This invention has as an object a belt sanding machine embodying a structural arrangement which is particularly economical to manufacture, which operates more efficiently and with less power consumption and requires less maintenance.

The invention has as a further object a drive mechanism between the motor and the driving roll, which mechanism functions to transmit the power from the motor without any slippage and/ or generation of heat, and with a minimum of friction loss.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

ln describing this invention, reference is had to the accompanying drawing in which like characters designate corresponding parts in all the views.

In the drawings- Figure 1 is a side elevational view of a sanding machine embodying my invention, the view looking to the right relative to Figure 3.

Figure 2 is a side elevational view of the machine looking to the left, Figure 3.

Figure 3 is a sectional view taken on a line corresponding to line 33, Figure 2.

The sanding machine consists of an integral cast metallic frame structure having a flat top wall from one side edge of which a vertically disposed side wall 11 depends. In its central portion, the frame member is substantially U-shaped, having a bottom wall 12 extending in spaced parallel relation to the top wall 10, this bottom wall forming a shoe over which the lower run of the abrasive belt 13 travels in a rearward direction, or to the left, Figure l. The frame is provided with a structure at 14 for supporting a yoke 15 in which the idler roll 16 is journalled, this roll being positioned at the forward end of the frame structure. The yoke and its supporting structure is more particularly described in the co-pending application of Lars Frostad, Ser. No. 437,687, filed June 18, 1954, now Patent No. 2,742,741, dated April 24, 1956. A motor housing 20 is arranged on the top wall 10 and preferably, as here shown, is cast integral therewith and in which the driving motor is mounted with its armature shaft 21 extending transversely of the frame and having an end portion 22 extending outwardly beyond the plane of the side wall 11. A belt pulley 23 is fixedly secured to this extending portion 22 of the 2 armature shaft as being threaded thereon, see Figure 3.

The side wall 11 is formed, at the rear end of the frame structure, with a recess 24 provided with a closure cap 25 affixed thereto as by screws 26. A shaft 28 is journalled in the side wall 11 and has aflixed to its inner end the driving roll 29. Adequate support for the shaft 28 is provided by an inwardly extending boss 30 cast integral with the side wall. The shaft 28 has an end portion 31 extending into the gear compartment 24 and provided with a spur gear 33 affixed to the shaft as by a pin 34.

The recess 24 forms a gear compartment in which a reduction gearing of the drive structure is mounted. A jack shaft 35 is mounted in the gear compartment 24, the inner end of the shaft being journalled in a bushing 36. The shaft 35 has a portion 38 extending outwardly through an anti-friction bearing 39 mounted in the compartment closure 24. A belt pulley 4G is fixedly mounted on the outer portion 38 of the jack shaft, as by being threaded thereon, and the jack shaft is formed intermediate its ends with a pinion gear 41 which is arranged in mesh with the gear 33.

The pulleys 23, 40, are arranged in alignment and are preferably of the gear tooth type to accommodate a cog belt 42. The pulley '40 is of substantially greater diameter than the pulley 23 to effect proper speed reduction from the high speed armature shaft 21. Also, the gear 33 is of substantially greater diameter than the pinion 41, effecting a further speed reduction and providing the necessary high torque to effect operation of the belt 13. The pulleys 23, 40 and the belt 42are arranged in a compartment formed by a closure or cover member 44 detachably secured to the frame, as by screw 45, threaded into a boss 46.

The armature shaft is provided with a fan 50, which functions to draw air inwardly through openings 51 formed in the end cap 52 of motor housing 29, about the motor components, and discharging an air blast through openings in the opposite end wall of the housing 26. One of these latter openings, as opening '53, communicates with the belt compartment. This arrangement effects cooling of the belt 42, and further maintains a slight air pressure within the enclosure, thereby preventing the entrance of abrasive dust in the enclosure. Here- -tofore, belt drives on sanders of this type have not been economical because of the abrasion of the dust between the pulleys and the belt.

With this arrangement, the cog belt provides a reduction drive from the motor to the jack shaft, without slippage and without requiring the application of a lubricant. The high torque transmitting portion of the drive is through the gear reduction 33, 36, which is confined within the gear compartment 24 and which is lubricant tight whereby the lubricant does not drip out on the work being finished by the sander.

Due to the fact that there is no slippage between the pulley 23 and the cog belt 42, no heat is generated by friction at the pulley. Due to the cooling effect of the fan 50, no heat is generated by the flexing of the belt as it travels about the small pulley 23 of the high speed universal motor. This effects a lower operating temperature of the motor and housing 2i) and in turn permits the machine being provided with a metallic handle 55 cast integral with the frame. The power supply cable 56 enters through the top portion of the handle and is connected to the windings of the motor through a switch positioned in the handle and actuated by a trigger 57. The handle is provided with a removable side plate 58 attached, as by screws 59, to the handle proper. The upper portion of the handle is formed integral with the motor housing 2%? and the lower portion formed integral with a curved wall 60 curving downwardly from the top I wall 10, in spaced concentric relation to the rear pulley 29. A handle knob 62'is attached to the forward side of the motor housing 20for the convenient manipulation of the machine. a i

What I claim is: r V g 1. A power operated, bodily manipulable belt sanding machine comprising a frame having a top wall, a verthe top wall, a motor "housing on the top wall, a motor mounted in the housing and having its power shaft extending transversely of said top wall and having an end portion projecting outwardly from the plane of the side wall, a belt pulley fixed to said end portion of the motor shaft, said side wall being formed'with a recess in its outer surface in proximity to the rear end of the frame to provide a gear compartment, an idler roll journalled at the forward end of the frame, a shaft ournalled in the rear end portion of said side wall and extending transversely below said top wall, a driving roll fixed to the inner end of said shaft, the outer end of said shaft extending into saidrecess, a closure for said recess forming in conjunction therewith a grease tight gear compartment,

a jack shaft journalled in said gear compartment and" having an end portion extending outwardly through'said closure, gearing arranged in said'gear compartment and operatively connecting said jack shaft to said driving roll shaft, a pulley fixed to the extending portion of said jack shaft, the periphery of said pulleys being formed with cogs, and a cog belt trained over said pulleys.

2. A portable self-contained power-operated belt sander comprising a frame including a top wall, a side tically disposed side wall depending from a side edge of jack shaft a closure member detachably secured to the frame and forming a compartment for said belt drive, s'aid motor housing being formed with an aperture communicating with said belt compartment, a fan'mounted on I said motor shaft in said motor housing and being operable to circulate an air current through said belt compartment, an idler roll jotirn'alled at the forward end of the frame and anabrasive belt trained over said rolls for movement lengthwise offthe frame below said top wall.

3. A power operated, bodily :manipulable, bel-t sanding machine comprising an integral frame havinga top wall, a vertically disposed side wall depending from -a longitudinal side edge of the top wall, and a motor housing extending transversely of the top wall at substantially the mid point thereof, a motor mounted in said housing and having an end portion of its power shaft projecting outwardly from the plane of said side wall, said side wall being formed with a recess in proximity to the rear end of the frame to provide a gear compartment, a closure member overlying said recess and being detachably secured to said sidewall and forming, in conjunction with said recesses, a grease tight gear compartment, a jack shaft jou rnalled in said gear compartment and having an end portion extending through said closure externally of the plane of said side wall, belt pulleys fixedly secured to said extending ends of the motor shaft and jack shaft respectively, a drive belt trained over said pulleys, a cover wall depending from one longitudinal edge of the topfl wall, a mot-or housing on said top wall, said side wall being recessed at the rear portion thereof to form a gear compartment, a'shaft journalled in said side wall and having an end portion'extending' transversely. below the top wall, an abrasive belt driving roll mounted on said end portion of the shaft, the opposite end-of said shaft.

extending into said gear compartment, a jack shaft journalled in said gear compartment, gearing arranged in said compartment opera-tively connecting said first-mentioned shaft and said jack shaft, said jack shaft having an end portion extending exteriorly of the plane of said side wall, a motor mounted in said motor housing and having a power shaft extending outwardly from the plane of said side wall, a cog belt drive arranged exteriorly of said side wall and operatively connecting said motor shaft to said member detachably secured to the frame and forming an References Cited in the file of this patent UNITED STATES PATENTS 2,260,949 Mall Oct. 28,1941 2,272,273 Parker Feb. 10, 1942 2,317,522 Curtis 3 Apr. 27, 1943 2,621,453 Oren Dec. 1176, 1952 2,654,190 Mitchell Oct. 6, 1953 

